Cellular structure



Nov. 2, 1937. J. PAvLEcKA CELLULAR STRUCTURE Griginal Filed Jan. 13, 1933 3 Sheets-Sheet 1 y IN VE NTORI ym /zm/ Nov. 2, 1937. J. PAvLEcKA CELLULAR STRUCTURE 3 Shee 11s-Sheet 2 Original Filed Jan. l5, 1953 I N V EN TOR.

Novf 2, 1937. J. PAvLEcKA CELLULAR STRUCTURE s sheets-sheets Original Filed Jan. 13, 1933' Dn O T. N E V m Patented Nov. 2, 1937 UNITED STATES PATENT Y.oli-"EicE John Pavlecka, Detroit, Mich.

Application January 13, 1933, Serial No. 651,494

Renewed March 2, 1936 7 Claims.

My present invention relates to a variety of generic structures having a large load supporting surface, such as floors, walls and Wings of aircraft.

The purpose of my invention is to devise a structure of the character above mentioned that Will sustain most load and weigh least.

Another object is to provide a. `structure for supporting loads distributed over a large area, hereinfurther referred to as the plane type, that will utilize mainly sheet material and will be easy to fabricate. y

A still further object is to devise a structure of the-above character that will be easily dismantled 4and re-assembled at any time for purposes of inspection or replacement of any one of its component members.

A structure of the plane type must sustain-not only direct weight distributed or concentrated on its surface, but must also resist compressive and tension stresses induced in its body by bending, and must, furthermore, withstand bending and shear forces in its border extremity at its points of attachment to other bodies. These requisites are'met inthe structure of my invention by supporting the direct weight by sheet material whichforms therexterior surfaces of the structure, by resisting the termi-nal forces by relatively rigid and ycompact members, such as rods or tubes embodied in the structure, and by opposing the 4induced stresses within the structure by the combined action of the sheet vmaterial which constitutes the body of the structure, as well as the individual rigid -members incorporated in the sheet material. A

The novel features through which the above principle is materialized will now be disclosed in Adetail as applied to the severalembodiments il.- lustrated in the drawings pertaining to thisuspec'ification and formingran integral part thereof.

In the drawings, A f Fig. 1 represents a transverse cross-section throughs. typical structure of the plane type.

'Y Fig. 2 is a similar Vcross-Section showing lcertain internal stiffening `elements for greater strength.

Fig. 3 is a transverse cross-section through ,another .example of the structure of my invention, this one showing` triangular conguration Which will be referred to asdiagonal truss.

Figsi, 5, and Gare perspective views relating ,to the preceding embodiments and depicting mainly the manner in which the rigid members are incorporated in the body of the structure, and

the `mannerlof holding the `sheet material in the f longitudinally a rectangular sheath; into each of body together by means of the same rigid members. l Referring to Fig. 1, theplane type of structure represented in this view is characterized externally vby extendedproportions in its length and width but by a relatively `small thickness. As a I whclethestructure may be either a continuous span ,or a cantilever carrier, and moreover,v it may be of uniform proportions throughoutits' extent or it may taper in Width or Yin thickness, or in both towardone extremity. The body'of the structure is an assemblage .of Aa series of individual tubular elements, hereinfurther calledj cells, eX- tending lengthwise of thestructure side by side, The cel'lsare generally polygonal. or multi-lateral, byA which terms I designate any geometrical or irregular shape having .at` least vtwo sides meeting in as many welldenedapices.

The cells in the structurein Fig. l are all alike, being rectangularinshape and comprising each two 20 chord webs I and2,and two side -webs 6 and'l, the former providing the bottom and the Vtop exterior surf aces of the structure, respectively, and' the lat-l ter abuttiingronthe sides of theadjacent cells. The p chord webs l air-id 2 meet the side'Webs 6 and 'I in 25 founapices, which apices are;v profile igrooved'laterf ally and outwardly for the Iwhole extent of the cells, the profile of the grooves in this particular `caselbeing rectangular, as shown `on a larger scale in Fig.4. The grooved apices of the cells are transversely serrated throughout theirlen'gth, theserkrations being eoluidistant` portions of the apex .grooves cut out to 4a certain deptliin each two associated cells the serrations are relativelystaggered lengthwise so .that when, on assembly, the 37. l

.cells are abutted one onto each other, the serrated portionsl ofy each cell Will intermesh withv the Vfull apex Vportions 3 .of the adjacent cell or .cells in a hinge-like manner, thereby forming these sheaths is thrust -on'errigid strut 5 which interlocks the cells-into unity after the fashion `of a hinge pin.

VThe cells are fabricated. of sheet material of suitable gauge tov withstand not only local strain but also be able to partake in compressive loads in cooperation with the struts 5. The material in the cells may be steel, duralumin, fibre, or any other. Thel cellsare fabricated as complete units `50 ready forassembly into the structure; this is done "A" by bending or rolling she-ets into closed tubular shapes with the apex grooves rolled or embossed in and the serrations punched out. preferably'in Y flat stock. The closing seam is located preferpi5 ably in one side of the cells, as shown, and is either welded or riveted, as by rivets 8.

As a means of gaining additional stiffness for the side webs 5 and Lilanged holes 8 are punched in them, these holes being spaced so as to clear the heads of the rivets 9, as shown. Corrugations Y or embossed beading may be substituted for the holes 8.

The struts 5 are linear members, by which fterrnV Y I designate either a tubular or a prismatic beam of any geometrical or irregular shape to suit any particular embodiment.V Functionally, the struts 5, in addition to tying up the cells into a unit, are intended to sustain primarily the bending and the shear forces at and between the terminal points of the structure, provide these terminal points of attachment or suspension of the structure to other bodies, and reinforce the sheet material against local buckling. The struts 5 are, in turn, reinforced by the sheet material of the cells due to the restraining hold that the grooved apex portions of the cells have on them. The cross-section of the struts 5 may, in certain embodiments, be made to correspond to the intensity of stress in them, i. e., the thickness of their walls may be increased toward the point of attachment by splicing a piece of a smaller section into them, or, in case of a` cantilever structure,

. the whole cross-section of the struts may taper longitudinally. 1

Fig.v 2 represents substantially the same type of structure as Fig. 1 with an improvement' residing in that the side webs 6 and YI of the cells between the grooved apex portions 3 and 4 are indented inwardly; in this case they are shown as true circular arches so that the adjoining webs o f each pair of associated cells give rise `to a round Vtubular spar within the structure. These spars will materially increase the carrying capacity of the structure by virtue of their' inherent stiffness as hollow beams. The struts 5 in this case are shown as being round in crosssection as also shown in Fig. 5. f

VVA type of structure which embodies all the new features of the preceding types and discloses a further'novelty inthe manner of assembling the cells is shown in Fig. 3, and on a larger scale in Fig. 6. Y

In this embodiment the cells are distinguished by their triangular shape and-.by the fact that only two of their apices are serrated, these being the two apices at the chord webs I and Il at the bottom and top, respectively; the third apex is continuous. The cells are assembled in such a manner that the top and bottom surfaces of the structure are provided by two rows of cells, the cells forming one surface alternate with those forming the opposite surface and each row of cells is interlocked at the chord apices of its cells.

The side webs 6 and 1 of each pair of one intermediate and one alternate cell abut onto each otherthereby forming a double diagonal truss web. In order to retain the two rows of upright 'and inverted cells together, the side webs B and 1 of each pair of one upright and one inverted cell The struts 5 are preferably triangular in crosssection whereby they will conform to the natural profile of the cell apices and will dispense with special profiling of these apices.

I claim:

l. A structure comprising, a series of tubular 'multi-lateral cells having side webs and chord apex portions of the associated cell, and linear members interlocking said intermeshed apex portions of said cells.

2. A structure comprising, a series of tubular cells extending lengthwise of the structure and having side webs and lchord webs meetingV in a number of apices, said cells providing the exterior surfacesV of said structure with said chord webs and abuttingone on Veach other along said side webs thereby formingA walls of double thickness in the interior of said' structure, each cell having its apices prole'grooved and transversely serrated, said serrated apices of each'twofassociated cells being intermeshed, linear. members interlocking said intermeshed apices, and-means for stiffening said side Webs of said cells between said apices thereof. i

3. A structure comprising, a series of tubular cells extending lengthwise of the structure and having side webs and chord webs meeting in aV number ofapices,` said cells paralleling one an-v other and providing the exterior surfaces of said structure with said chord webs thereof, each cell having its apices prole grooved and transversely serrated, said serrated apices of each two associated cells being intermeshed,lan d linear members interlockingsaid intermeshed apices; said side webs of said cells being arched between said intermeshed apices thereof whereby each group of associated cells will give rise to a tubular spar within said structure. l

4. A structure comprising, a series of substantially rectangular tubular'cells extending lengthwise of the structure and having each two side webs and two chord webs meeting in four apices said cells providing the exterior surfaces of said structure with said chord webs and abutting one on each other along said side websV thereby form,- ing walls of double thickness in the interior of said structure, each cell having the apices thereof profile grooved and transversely serrated, said serrated apicesof each two associated cells being intermeshed, and substantially rigid linear members interlocking said intermeshed apices.

Y 51A structure comprising, a series of substan- Vtially rectangular tubular cells extending lengthwise of the structure and having each two side webs and two chord webs meeting` in four apices,

said side webs being arched inwardly between said apices, said cells parallelingk one another with said chord webs thereof providing the exterior surfaces of said structure and said side webs of each two adjoining cells forming -a tubularI spar within said structure, each cell having the apices thereof profile grooved and transversely serrated, said serrated apices of each two associated cells being intermeshed, and substantially rigid linearmembers interlocking said intermeshed apices. Y

6. A structure comprising, a series of substantially triangular tubular cells extending lengthwise of the structure and having each two `side webs and one chord web meeting in three apices, said cells abutting one on each other inversely whereby all alternate cells will provide with said chord webs thereof one exterior surface of said structure and all intermediate cells the other surface, said side webs of each two abutting cells forming a double diagonal truss between said exterior surfaces, each cell having the two apices thereof at said chord web transversely serrated and intermeshed with the apices of the associated cells, each pair of one alternate and one intermediate cell being conjoined in said side webs thereof, and substantially rigid linear members interlocking said intermeshed apices.

7. A structure comprising, a series of substantially triangular tubular cells extending lengthwise of the structure and having each two side webs and one chord web meeting in three apices,A

said side webs having flanged holes punched therein with the flanges turned inwardly, said cells abutting one on each other inversely'whereby all alternate cells will provide with said chord webs thereof one exterior surface of said structure and all intermediate cells the other surface, said side webs of each two abutting cells forming a double diagonal truss between said exterior surfaces, each cell having the two apices thereof at said chord web transversely serratedand in-v termeshed with the apices of the associated cells, each pair of one alternate and one intermediate cell being conjoined in said side webs thereof between' said flanged holes therein, and substantially rigid linear members interlocking said intermeshed apices.

' JOHN PAVLECKA. 

